The present invention relates to a device for closing road wells in vehicle and pedestrian areas. It is known that devices for closing road wells formed underneath road surfaces or open areas and intended for the most varied uses, for example for housing the valves and connection nozzles of tanks or cisterns, generally comprise a support frame stably fixed to the ground with cement mortar or other similar materials and defining an opening for access to the underlying cavity, and a plate element matching the edge of said access opening so as to close the latter with its own weight.
The plate element normally consists of a considerable mass of grey iron, for example of about 90 to 100 kg, in all cases in which said plate element and the corresponding access opening are, for functional reasons, of large sizes. In fact, the plate element must have a thickness suitable for withstanding stresses and weights even of a significant nature, such as those imparted by vehicles which may pass on it, without undergoing substantial flexural deformations or being displaced from its seat.
Opening a device for closing road wells of the type briefly described above involves carrying out a fairly difficult and physically tiring operation since two persons are required for simultaneously exerting a raising force by means of suitable tools or special spanners which can be inserted into and rotated inside appropriate holes formed in the plate element.
The latter, once it has been raised and separated from the support frame, is placed alongside the access opening. A similar operation must be performed when the plate element is to be rearranged to the closed position.
It is obvious, therefore, that the cast-iron plate elements of the known type, in particular when frequent opening and closing operations must be performed, in addition to not being very practical for use owing to the necessary presence of two persons, also offer a limited degree of safety, since the manual displacement of a metal mass of considerable weight may easily cause damage and injury to the involved workers.
It has already been attempted to overcome the abovementioned drawbacks by constructing the plate elements using cast iron with improved mechanical strength characteristics, such as nodular cast iron, so as to be able to reduce their mass and hence the effort required for the opening and closing operations.
However, this known technical solution, in addition to involving in any case an operation which can be performed only by at least two persons, has proved not only to have a high cost owing to the improved qualities of the material used, but also not to be entirely functional. In fact, since these plate elements have a limited thickness and hence also a considerably smaller mass, for the same admissible load levels as those of plate elements made of grey iron, they may be more easily deformed or dislodged from the seat inside which they rest only with their weight, owing to the repeated thrust forces which are normally imparted to them by vehicles.